Igniter composition

ABSTRACT

An exothermic pyrotechnic composition suitable for the ignition of gas generating candles to be used for the generation of gases in a confined volume is disclosed. The incorporation of borax into a conventional iron-chlorate type igniter composition substantially reduces the propagation rate and causes the formation of a highly adherent slag. Taken together, these features reduce the likelihood of the igniter compound exploding from the surface of the material to be ignited and of the generation of gases from the ignited composition at a rate sufficient to overpressurize the volume.

[ Oct. 30, 1973 Hyer [ IGNITER COMPOSITION [75] Inventor: Harry J. Hyer, Los Gatos, Calif.

[73] Assignee: United Aircraft Corporation,

Hartford, Conn.

[22] Filed: Sept. 17, 1971 [21] Appl. No.: 181,641

[52] U.S. Cl 149/18, 149/37, 149/42, 149/44, 149/85 [51] Int. Cl. C06c 9/00 [58] Field of Search 149/18, 37, 42, 44, 149/85 [56] References Cited UNITED STATES PATENTS 2,545,076 3/1951 Ellenbogen 149/85 X 3,046,728 7/1962 Fitzpatrick 149/37 X 3,160,537 12/1964 Trafton 149/37 3,259,972 7/1966 Long 149/37 X 3,338,763 8/1967 Kristal [49/85 X FOREIGN PATENTS OR APPLICATIONS 20,494 10/1910 Great Britain 149/85 Primary ExaminerCarl D. Quarforth Assistant Examiner'E. A. Miller Attorney-Steven F. Stone [57] ABSTRACT An exothermic pyrotechnic composition suitable for the ignition of gas generating candles to be used for the generation of gases in a confined volume is disclosedv The incorporation of borax into a conventional iron-chlorate type igniter composition substantially reduces the propagation rate and causes the formation of a highly adherent slag. Taken together, these features reduce the likelihood of the igniter compound exploding from the surface of the material to be ignited and of the generation of gases from the ignited composition at a rate sufficient to overpressurize the volume.

6 Claims, No Drawings 3 ,769 106 1 2 IGNITER COMPOSITION nited or compacted into the proper shape and then ap- BACKGROUND OF THE INVENTION plied to the surface to be ignited and dried thereon. Since the igniter is normally compounded with water,

In various gas generating systems known to the prior the borax can be added as such or can be formed in situ art, an exothermic gas generating composition is pro- 5 from any of the incompletely hydrated forms of Na B- vided with a more readily ignitable composition which, The amount of borax to be used depends upon the in conjunction with an ordinary fuse or electric match, degree of suppression of the propagation rate that it is provides the ignition train for the ignition of the main desired to obtain. Thus, for example, small amounts of body of gas generating material. See for example, U.S. borax will produce some effect and 5 percent of borax Pat. Nos. 2,98l,6l6, M. H. Boyer, for Gas Generator has been found to produce over 50 percent reduction Grain, Apr. 25, 1961 3,293,187, M. M. Markowitz, in the propagation rate of a comparable material with- Oxygen Generating Products, Dec. 20, 1966 or R. M. out the borax. Higher amounts of borax could also be Bovard et al., 3,5 l6,797 for Chemical Oxygen Generaused but, in most cases, it is not necessary to reduce the tor, June 23, 1970. Satisfactory ignition of these types rate below that obtained with about 5 percent borax. of pyrotechnic mixtures as well as of the thermite type 5 The effect of borax on typical igniter compositions is compositions require that an igniter material of high readily apparent from the inspection of Table I which caloric output be held in intimate contact with the mass contains results of two runs for each composition.

TABLE 1 (Percent by weight) I 11 Ill IV V VI Vll VIll I IX X Fe 30 3O 30 3O 30 30 6O 57 NaClO;,.. 32 32 37 32 32 32 32 32 32 35.l5 M 0 27 27 27 32 27 27 27 27 2 1.9 Dextrin 5 5 5 5 5 5 5 5 l 0.95

Asbestos N82B401' v HqBO-g NaJPOQ' lOH-O. (ammo kiiiikfiifrmi "as "473 "'51s "4:5" 4:9 6.9 4.7 3.7 H. Rate (in/min), run 2 6.] 4 7 5.9 4.4 4 4 6 5 4.8 3.8 l 7 of pyrotechnic material to be ignited for a period of As can be seen, Formulation 1 containing 5 percent time sufficient to permit the initiation of self-sustaining borax had a substantially lower propagation rate than exothermic reaction in the body of the pyrotechnic ma- 35 any of the comparable Formulation II, III or IV which terial. The igniter obviously must be more readily igcontained, instead of the borax, an additional 5 percent nited than the main mass of pyrotechnic material and or iron, chlorate, or aluminum oxide, respectively. Sim i i i mixtures f fi l powdered metals such as ilar results were obtained with the borax containing iron, boron, titainium, zirconium, or magnesium tocomposition X when compared with the comparable gether with a suitable oxidizing agent such as a chlorate 40 non-borax containing composition IX. In a d t or hl i h or ith t inert a h forming, borax produced a greater reduction in propagation rate than any other additive tested (Formulations V-VIII) DESCRIPTION OF THE INVENTION which include both boron containing and highly hydrated compounds. Further, the effect of borax appears The incorporation of borax into an iron-chlorate igto be unique to iron-chlorate compositions since tests niter com ositi s b i ll reduces h pmpagahave shown it not to function with the iron-perchlorate tion rate of the composition and produces an ash which equivaleht with y of the conventional trat is highly adherent both to itself and to the composition g thermite, BKNOa aluminumupon which it is deposited. This invention is usable in Perchlorate-vegetable Oil (Al fign r ystems.

the iron-chlorate igniter compositions which consist of while this invention has been described with respect a mixture f i d a h1 i ll an li or to various embodiments thereof, it should not be conalkaline earth metal chlorate. The actual composition sh'ued as beihg limited Yarious odifications of the igniter mixture can be varied widely to obtain can be made y Workers Skilled in the art thout devariation in characteristics such as ignitability, for ex- P g from the PP of'the nti n which is limited ample, as is known to the art; but to function as an igy y the following ClalmS he eln:

niter, the ratio of iron to the chlorate should be on the I ciaiml I fuel-rich side of stoichiometric. If the composition conlin an ron-Chlorate igniter composition comprising {gins other oxidizable compounds uch as a binder of a fuel-rich mixture Of il'Oll and metal chlorates, the imdextrin, for example, sufficient chlorate should be pro- P m n herein said composition contains a burnvided to fully oxidize the oxidizable species while still s fate retarding amount of maintaining an overall fuel-rich mixture of iron to chlo- The composition f claim 1 wherein said metal rate, A a general l h more f L i h h ichlorate is selected from the group consisting of alkali tion, the easier it is to ignite. In addition to the iron, and alkaline earth metal chlorates. I chlorate and an organic binder, various amounts of ash cohipositioh eh claim 2 wherein a d r nforming and/or reinforcing materials such as aluminum chlorate g composition further bbmpl'lses ah oxide, asbestos and chopped glass fibers, for example, genie bindefmay be added as is known to the art. Typically, these 4. The composition of claim 3 wherein said ronmaterials are compounded in the form of a paste with chlorate igniter composition further comprises inert water and then either applied to the surface to be igstructural reinforcement.

5. The composition of claim 3 wherein said iron- 6. The composition of claim 4 wherein said ironchlorate igniter composition further comprises inert chlorate igniter composition further comprises inert ash forming agents. ash forming agents. 

2. The composition of claim 1 wherein said metal chlorate is selected from the group consisting of alkali and alkaline earth metal chlorates.
 3. The composition of claim 2 wherein said iron-chlorate igniter composition further comprises an organic binder.
 4. The composition of claim 3 wherein said iron-chlorate igniter composition further comprises inert structural reinforcement.
 5. The composition of claim 3 wherein said iron-chlorate igniter composition further comprises inert ash forming agents.
 6. The composition of claim 4 wherein said iron-chlorate igniter composition further comprises inert ash forming agents. 